Question

Tomas learned that the product of the polynomials (a + b)(a2 – ab + b2) was a special pattern that would result in a sum of cubes, a3 + b3. His teacher put four products on the board and asked the class to identify which product would result in a sum of cubes if a = 2x and b = 1.

Which product should Tomas choose?

A) (2x + 1)(2x2 + 2x – 1)
B) (2x + 1)(4x3 + 2x – 1)
C) (2x + 1)(4x2 – 2x + 1)
D) (2x + 1)(2x2 – 2x + 1)

Answer 1

(a+b)(a²-ab+b²)
(2x+1)((2x)²-(2x)(1)+1²)
(2x+1)(4x²-2x+1)


C is answer

Answer 2

General form: a^3 + b^3 = (a + b) (a^2 -ab +b^2)

Now replace with a= 2x, b = 1

(2x)^3 + 1^3 = (2x + 1) [ (2x)^2 -(2x)(1) + 1^2) = (2x + 1) (4x^2 - 2x + 1)

Therefore, the answer is the option C)